The present invention relates to a vehicle seat back frame and in particular to a seat back frame that is reinforced along one side of the frame with a weld plate framing closed cross-section.
The seat back frame in a motor vehicle seat assembly receives its most severe loading when a seat occupant attempts to reach into a rear pocket and, in so doing, leans rearward against the seat back, generally toward one side. With many reclining seat backs, the recliner mechanism is provided at one side of the seat back and carries all of the load applied to the seat back frame. When a seat occupant leans back in the seat, this load results in both a application of a bending load on a seat back frame and also, due to the lateral offset between where the load is applied and the side of the seat back frame with the recliner, a torsional load is produced in the seat back frame. Seat back frames have been strengthened by the addition of a reinforcing plate fastened along one or both upright sides of the seat back frame. However, such plates while providing reinforcing against bending, provide little reinforcement against torsion.
Accordingly, it is an objective of the present invention to provide a seat back frame that is reinforced in the region of the seat back recliner to increase the capacity of the seat back frame to accommodate both the bending and the torsional loads.
The seat back frame of the present invention includes a tube member bent to form a four sided frame member having first and second upright sides and generally parallel top and bottom ends with said ends being shorter in length than said upright sides. The tube ends are abutting one another and are welded together to close the frame member. A pivot member is coupled to the frame member adjacent a corner formed by a second upright side and the bottom end, forming a first pivot for rotatably mounting the seat back frame to a lower seat cushion.
An elongated weld plate is fixed to a first upright side of the frame member and extends, in length, more than half the length of the first upright side. The weld plate is U-shaped in cross section with the first upright side of the frame member disposed in the open end of the U-shaped cross section. The weld plate is welded at several locations to the frame member.
The lower end of the weld plate is formed for attachment of a second pivot member to the seat back frame forming a second pivot. The first and second pivots together define a lateral pivot axis for the seat back frame. The second pivot member is a part of a recliner mechanism used to hold the seat back in place.
An advantage of the seat back frame of this invention is that the weld plate together with the tubular frame member forms a closed cross section having significantly improved bending and torsional strength. This is accomplished easily while using a conventional and easily formed tubular seat back frame.
Further objects, features and advantages of the invention will become apparent from a consideration of the following description and the appended claims when taken in connection with the accompanying drawings.